Method of and apparatus for determining the shapes of airplane parts



Jan. 18 '1927. 1,615,063

G. o. BNARD METHOD OF AND APPARATUS FOR DETERMTNING THE SHAPES OFAIRPLANE PARTS Filed Dec. 19, 1925 Flas.

Patented Jan. 18, i927.

Ltiltl UNl'l'E S'llt'ltl PTNT OFFICE.

GEORGES LOUIS OLIVIER BNARD, OF BLOS, FRANCE.

Application filed December i9, 18?:5, Serial lilo. 275,523, and laFrance December 19, 1924.

Airplane constructors endeavour to give to their machines always greaterspeeds either by devising more powertul motors or by modifying theshaping ot the wings, shells, cross-ties, in a word ot all theconstructional parts oi' the machines.

Shapes or wings and ot shells are constantly being altered and suchalterations resuit rom investigations conducted to determine the drag otthe various parts through air. Dynamometer readings taken from reducedmot els stationary in tunnels do, indeed, show said drag, but allord noaccurate indications as to what alterations should be introduced inorder to obtain minimum drag at a given speed.

The object of my invention is to provide a process permitting todetermine in advance, by means ot laboratory experiments simple, prompt,and inexpensive, what shapes should best be given to constituent partsof an airplane 'for delined speeds ol, say, 150, 200, 250 or 300kilometers per hour.

My process consists in coating a reduced model or the airplane with agreasy material, solid but iusible at a temperature readily obtained inpractice. Said reduced model, so coated with greasy material, is thenexposed to a current of air heated up to the temperature equal to themelting point of the greasy material. Under such conditions, the greasymaterial will be melted or peeled oli' the quicker and the morethorougl'ily where the drag is greater, and, according to the locationand degree ot wear shown by the tested pieces, it can then beascertained what alterations should be made in the prime model tominimize drag at any given speed.

My process will also permit accurately to determine eddies, theirimportance, reciprocal reactions on the wings orc several-decked planes,etc., etc.

Again my process will allow the .safety of machines to be increased bypermitting investigation of possible alterations in the main parts,while reducing to a pre-admitted minimum the inconveniences or drawbacksinvolved by the modilications brought to the outer forms.

Lastly my process, as applied to the designing of propellers and ofprojectiles or o;t` any other bodies moving through air, will aiiford toa certain extent valuable hints concerning how best they should beshaped.

The solid greasy materials that l would easily be heated.

propose to use may be; for instance, parat'- n'ne, stearine, spermacetior such like, the melting points of which are over 36o G. to permithandling thereof and below 650 C. a'teinperature up to which the airblast can The melting point of the material used should, preferably besomewlicre between t5 and 650 C.

in order to make my invention more clearly understood l haveillustrated, merely as an example, an embodiment thereot in and by adrawing appended hereto and wherein:

ltigure l is a longitudinal section of my device.

Figure 2 is a plan view of the same.

Figure 8 is a cross section thereof.

in all the iigures the same reference letters denote the same parts.

My device comprises essentially an openendcd metal or wooden cylinder tof a suitable size, preferably 2 meters in diameter' and e meters long.it is located in the center of a chamber b about 8 meters long by meterswide and meters high; these dimensions being, ot course, given merely byway oit example and subject to numerous alterations.

at one ot the cylinder ends is positioned a powerful lian c and, behindsaid fan, a grate d intended to straighten the air currents produced bythe ran. TWithin chamber b and, 'tor instance, on either side ofcylinder or tunnel a radiators 7" are litted up.

The reduced models to be experimented with are suspended by any suitablemeans inside cyiinder a, after having been, of course, coated withparailine or such like material. ll then raise the temperature in thechamber b until it reaches the melting point or' the greasy materialused, and cause the tan to be operated at such a speed as will impart tothe air current or blast the desired velocity. l. allow operation to goon for some moments, then stop the fan, cool the chamber and withdrawthe model. y

llihere the blast has met with the greatest resistance, the greasymaterial will have been melted and blown oft.

W here the blast has met with no resistance the parts tested will haveundergone no n'iodilication.

lnspection oit the parts experimented with will show the kind andimportance of the alterations to be introduced.

l claim as my invention:

l. In a method of determining the shapes iii) of airplane parts, thesteps of coating a re duced model of an airplane with a solid greasysubstance having a low melting point; and blowing against the coatedmodel, while in suspended position, a current of air heated to themelting point of the coating substance and traveling at the velocity inView of Which the t'orm or shape of the model is to be determined.

2. In a method of determining the shapes of airplane parts, the steps ofcoating a reduced model of an airplane with a solid greasy substancehaving a lon7 melting point; suspending the coated model in anopen-ended cylinder dispose-d Within a closed chamber; and blowingthrough such cylinder, so as to impinge against the suspended model, acurrent of air heated to the melting point of the coating substance andtraveling at the velocity in viewv ot which the form or shape of themodel is to be determined.

3. In a method of determining the shapes of airplane parts, the stepsoi" coating a reduced model oi' an airplane with a solid l greasysubstance having a melting point between l5 and 65 C.; and blowingagainst the suspended model a current of air heated to the melting pointof the coating substance and traveling at the Velocity in View ot'.which the form or shape oil'I the model is to be determined.

l. Apparatus tor determining the shapes of airplane parts, comprising aclosed chamber ot large capacity; an open-ended cylinder supported inhorizontal position in the center of the chamber, and from the top Wallot which a red ced model of an airplane coated with a greasy substanceis adapted to be suspended; a tan located at one end ot the cylinder forblowing a current of air therethrough at the required velocity so as toimpinge against the suspended model; and heating means for raising thetemperature oit' the air current to the melting point of the coatingsubstance.

5. Apparatus according to claim 4, in which a grate is disposed in thecylinder adjacent the end Where the lan is located, to direct thestreams of air in straight lines toward the model.

In testimony whereof I aiiX my signature.

GEORGES LUlS OLVER BNARD.

